Inter population variation in behaviour of native prey (Daphnia) mediates the impact of the invasive spiny water flea (Bythotrephes cederströmii)on plankton communities

Abstract

AbstractPredation plays an important role in structuring and maintaining ecological communities. Population level differences in predator trait expression have been shown to influence predator impacts on prey species, altering ecological interactions and trophic dynamics. However, the effect of inter-population differences in prey traits on the impacts of predation on ecological communities remains poorly understood, especially for introduced predators where differences in prey traits could influence the outcome of biological invasions. We examined if population level differences inDaphniavertical position influenced the impacts of the invasive predatorBythotrephes cederströmiion major zooplankton and algal groups. Our results show that differences inDaphniavertical position resulted in differences inBythotrephesimpacts on small cladocerans, with a larger reduction small cladoceran density in mesocosms whereDaphniaadopted a deeper vertical position. Furthermore, we observed a greater increase in algal biomass in invaded mesocosms with a greater proportion of hypolimneticDaphnia. Taken together, these results suggest that population level differences inDaphniavertical position influence the magnitude and type ofBythotrephesimpacts on zooplankton communities.